The lawsuit, filed in U.S. District Court in Arizona, aims to enforce compliance with rules the agency adopted 38 years ago to guide recovery of the federally endangered species driven to near extinction by wolf extermination campaigns of the 19th and 20th centuries.

It asks the court to declare the agency in violation of the Endangered Species Act, and order it to “prepare and implement a scientifically based, legally valid” final recovery plan within a year of the court’s judgment.

The Mexican gray wolf was reintroduced into a small area of eastern Arizona and western New Mexico in 1998 as part of a strategy to reach a population of 100 wolves, including 18 breeding pairs, by 2006.

Today, the population stands at 83 wolves, and five breeding pairs. They are managed under restrictions that do not permit the mobile, clannish hunters to colonize new territory, increasing the likelihood of inbreeding, according to the lawsuit. The restrictions also allow excessive killing and removal of wolves that take livestock, the lawsuit says.

By the agency’s own assessment in a recent draft environmental impact report, the existing population is “considered small, genetically impoverished, and significantly below estimates of viability appearing in the scientific literature.”

Plaintiffs including the Defenders of Wildlife, the Center for Biological Diversity, the Endangered Wolf Center, the Wolf Conservation Center and David R. Parsons, a biologist who served as the agency’s Mexican gray wolf recovery coordinator from 1990 to 1999, accuse the agency of yielding to political pressure from ranchers, hunting groups and state officials in Utah, Arizona and Colorado.

In a letter to former Interior Secretary Ken Salazar in late 2011, for instance, Utah Gov. Gary R. Herbert urged that Colorado and Utah be excluded from what he described as “the Mexican gray wolf equation,” on grounds that those states were not “within its core historic range.”

The agency, in 2013, published documents based on recent genetic research showing that the species scientists know as Canis lupus baileyi ranged as far north as Utah and Nebraska.

“Unfortunately, when confronted with views from various interest groups — particularly livestock industry organizations, state wildlife agencies and the less enlightened hunting organizations – the agency takes a head-in-the-sand approach,” Parsons said in an interview. “What seems to be driving things in this case are the politics surrounding the Mexican gray wolf.”

Since 1982, the agency has convened three different scientific teams to prepare a formal recovery plan for the Mexican gray wolf.

The most recent effort produced a draft recovery plan in 2012 that recommended establishing two additional Mexican gray wolf populations, one in the Grand Canyon and another in the southern Rocky Mountains of New Mexico. The overall goal was to create three self-sustaining sub populations totaling 750 wolves.

The plan also suggested several areas of suitable habitat for reintroduction efforts including land in Arizona, New Mexico, southern Utah and southern Colorado.

That plan, however, was never published, and the recovery team that produced it never reconvened to review the proposal’s viability, according to the lawsuit.

“The agency has caved in to demands of the anti-wolf states,” Noah Greenwald, endangered species director at the Center for Biological Diversity, said. “Meanwhile, decades after it decided to reintroduce it into the wilds, the Mexican gray wolf remains on the precipice of extinction.”